Portable tools of such kind, also having the hydraulic piston/cylinder assemblies described, are already known in many different forms. For example, WO 99/19947 A and U.S. Pat. No. 6,532,790 B2, U.S. Pat. No. 6,401,515 B2, U.S. Pat. No. 6,276,186 B1, or U.S. Pat. No. 6,230,542 B1, WO 02/062504 A1 and U.S. Pat. No. 7,065,995 B2, WO 03/084719 A2 and U.S. Pat. No. 7,254,982 B2, U.S. Pat. No. 7,412,868 B2, or U.S. Pat. No. 7,421,877 B2 and EP 2 011 605 A2 and US 2009/0008118 A1 may be cited as examples of the prior art. In this context, the cited documents WO 02/062504 A1 and U.S. Pat. No. 7,065,995 B2 relate to an expanding apparatus, but the apparatus is of a kind in which expansion is effected by compressing an elastic rubber expansion element.
An expanding apparatus that is powered by an electric motor and actuated hydraulically, in which spreading segments actuated by an expanding mandrel are provided is also known from DE 102 47 549 B3.